Torque motor

ABSTRACT

An output shaft has coaxially secured thereto a generally cylindrically shaped rotor. The rotor has undulating opposite end surfaces characterized by a plurality of lobes. A carrier slidably supports a plurality of individual double-acting pistons. These pistons each carry a pair of bearings for engaging the end surfaces, respectively, of the rotor. A flow control device is connected with a suitable source of fluid pressure and includes poppet valves which are operated by cam means carried on the outer periphery of the rotor for controlling the flow of fluid to the pistons in predetermined sequence to cause rotation of the rotor and the output shaft.

1,781,068 11/1930 Michell 91/175 2,070,880 2/1937 Blum 91/175 2,115,556 4/1938 Maniscalco 91/188 2,434,747 l/1948 Ruben 91/175 3,105,415 10/1963 De Muth 91/188 FOREIGN PATENTS 228,313 2/1925 Great Britain 91/188 Primary Examiner-Paul E. Maslousky Alt0rneyHood, Gust, Irish & Lundy ABSTRACT: An output shaft has coaxially secured thereto a generally cylindrically shaped rotor. The rotor has undulating opposite end surfaces characterized by a plurality of lobes. A carrier slidably supports a plurality ofindividual double-acting pistons. These pistons each carry a pair of bearings for engaging the end surfaces, respectively, of the rotor. A flow control device is connected with a suitable source of fluid pressure and includes poppet valves which are operated by cam means carried on the outer periphery of the rotor for controlling the flow of fluid to the pistons in predetermined sequence to cause rotation of the rotor and the output shaft.

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TORQUE MOTOR BACKGROUND OF THE INVENTION The present invention relates to a hydraulically operated torque motor of the type adapted to provide high torque and relatively low horsepower. The invention is further directed to a piston-type hydraulic motor wherein reciprocation of the pistons causes rotation of a camshaped rotor.

Conventional piston-type hydraulic motors employ simple pistons with a roller or rollers near one end thereof. Some sort of a sliding bearing or crosshead must be added to carry the side thrust which produces the useful output torque, or the piston is allowed to carry the side load. In the latter case, the side thrust tends to cock the piston is the cylinder, causing binding and rapid wear. It is often necessary in prior constructions to provide suitable structure for preventing rotation of the pistons in the associated cylinders.

Known hydraulic torque motors also employ sliding direct the flow of fluid to and from the proper cylinders. Such sliding valves are of simple construction, yet they inherently cause leakage which allows the motor to creep" under an external load, and further permits some oil flow without causing the motor to operate. This discourages use of such motors in applications requiring the shaft to lock in position when stopped or to operate at extremely low speeds.

SUMMARY OF THE INVENTION In the present invention, an output shaft has a generally cylindrical, cam-shaped rotor coaxially secured thereto. The rotor includes undulating opposite cam surfaces facing generally in the same direction as the axis of the output shaft which define a plurality ofcam lobes.

A carrier or body slidably supports a plurality of separate pistons for movement in a direction parallel with the axis of the output shaft. Each of these pistons is of the double-acting type and has heads on the opposite ends thereof, respectively.

Each individual piston carries a pair of bearings engaging the opposite respective surfaces of the rotor.

Flow control means is connected with a suitable source of fluid pressure and includes a plurality of poppet valves for controlling the flow of fluid to the various pistons in predetermined sequence to cause rotation of the rotor and the associated output shaft.

The side thrust is applied at the axis of the doubleacting pistons in the present invention, thereby providing more uniform load distribution and minimizing the requirement for additional guides or bearings.

The bearings carried by the pistons are held in alignment with the rotor by means ofa close fit of a cutout portion in the pistons with the periphery of the rotor thereby eliminating the need for guides to prevent rotation of the pistons within the associated cylinders.

The use of poppet valves in the present invention materially reduces and in some instances eliminates leakage of fluid under pressure during operation, thereby enabling the motor to be positively locked in position and further enabling the motor to operate at extremely slow speed.

The arrangement of the present invention provides torque multiplication, eliminating gear reduction units which are often required with standard hydraulic torque motors.

In one design of this invention, configuration of the cam surfaces on the rotor is such that operation of an individual piston thereagainst produces variable torque, but the overall motor design is such that conjoint action of all of the pistons produces a torque which is practically constant. Other design features permit the motor to be of minimum size yet produce maximum torque.

The double-acting piston arrangement of the present invention produces a sliding bearing or crosshead effect minimizing the possibility of cocking and jamming as well as wear of the pistons.

A cam surface on the outer periphery of the rotor serves in operating poppet valves in timed relation upon rotation of the rotor for operating the pistons in time of sequence.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of one embodiment of the present invention partly sectioned for clarity of illustration;

FIG. 2 is an end view partly sectioned along line 2-2 of FIG.

FIG. 3 is a fragmentary sectional view taken substantially along line 33 of FIG. 2;

FIG. 4 is a side view of the carrier or body of the torque motor shown partly in section;

FIG. 5 is a fragmentary sectional view taken substantially along section line 55 of FIG. 2;

FIG. 6 is a side elevation of the cam-shaped rotor of the present invention;

FIG. 7 is an end view of the rotor shown in FIG. 6;

FIG. 8 is a fragmentary sectional view taken substantially along section line 8-8 of FIG. 7;

FIG. 9 is a fragmentary sectional view taken substantially along section line 9-9 of FIG. 7;

FIG. 10 is a view illustrating a portion of the rotor shown in FIG. 6 in a flat plane layout;

FIG. 11 is a fragmentary sectional view taken substantially along section line 111 1 of FIG. 10;

FIG. 12 is a schematic flat plane layout diagrammatically illustrating the flow control means operatively associated with the various pistons of the motor and in particular illustrating the valving and conduit connections to the various pistons;

FIG. 13 is a fragmentary sectional view of the manifold taken substantially along section line 13 -13 of FIG. 3 and which also shows in section the piston construction with the rotor removed;

FIG. 14 is a side elevation of one of the cylinder heads; and

FIG. 15 is an end view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings wherein like reference characters designate corresponding parts throughout the several views, as seen in FIG. 1, a stepped diameter output shaft 20 has a coaxial oil passage 22 for lubricant. This passage 22 has a fitting 24 at one end for connection with a source of oil (not shown), the opposite end of the passage 22 being in communication with a radial passage 26 which supplies lubricating oil to the outer surface of the shaft 20 and the associated elements.

A generally cylindrical, cam-shaped rotor, indicated generally by reference numeral 28, is coaxially connected for rotation with the shaft 20 as by welding at 2. In. etails of construction of this rotor are described hereinafter.

Referring to FIGS. 1 and 4, the shaft 20 and rotor 28 are rotatably supported within a carrier or body means 31 Whit. includes a pair of annular members 30 and 32 coaxially assembled to opposite sides of a central annular manifold 34, a pair of annular plates or cylinder heads 36 and 38 being secured to the opposite ends of the annular members 30 and 32, respectively. It should be understood that the motor is substantially symmetrical about a vertical plane extending perpendicular to the shaft axis and bisecting the manifold 34. Members 30, 32, 34, 36 and 38 are secured together by a plurality of screws 40, one being illustrated in FIGS. 1 and 5. As seen in FIG. 5, screws all are adapted to extend through holes 42 and 44 formed in members 36 and 30, respectively, the screws 40 being threaded into a tapped hole 46 in member 34. The screws M) are disposed in an annular array about cylinder head 36 for holding members 36 and in fixed position relative to member 34. It ill be understood that similar screws are provided in a like manner to hold members 32 and 38 in operative position with respect to member 34.

As seen in FIG. 4, annular members 30 and 32 have coaxial, enlarged, identical cylindrical bores and 52, respectively, which receive the output shaft 20. Member 30 has a plurality of bores 54 arranged in a circular pattern, these bores being eight in number and defining cylinders within which one end of associated pistons are adapted to slide. identically, but as a mirror replica, annular member 32 is provided with a corresponding number and arrangement of bores 56 which slidably receive the opposite ends of the pistons. The members 30 and 32, therefore, may be termed cylinder bodies.

Manifold 34 coaxially receives the rotor 28 and includes a plurality of part-cylindrical recesses 60 which are axial continuations of respective bores 54 and 56 in cylinder bodies 30 and 32 whereby the manifold 34 may also slidably receive the same piston (to be described later).

Each of the cylinder heads 36 and 38 is provided with a plurality of spaced tapped holes 64 to enable the motor to be mounted on a suitable supporting structure.

As seen in FIG. 1, an O-ring seal coaxially surrounds in sealing relation the shaft 20 and is held in place by a pair of snap rings 72. The shaft 20 is rotatably journaled within a first bearing 74 supported in cylinder head 36 and a like bearing in the other cylinder head 38.

An annular retainer plate 76 is secured to cylinder head 36 and is held in place by a plurality of screws 78. An O-ring seal 80 is seated within plate 76 and provides a seal with the outer surface of the output shaft 20. Plate 76 and screws 78 correspond to members 76 and 78 and are provided at the opposite end of the structure.

Referring now to FIGS. 6l1 inclusive, the construction of the rotor 28 is illustrated. It is generally cylindrical and includes undulating end surfaces and 92 which face generally in directions parallel with the shaft axis, these surfaces, however, having a slight slope, in the illustrated embodiment, of approximately 8.3 with respect to a radius as seen in FIGS. 8 and 9 so that surfaces 90 and 92 are disposed at an angle to the axis of the output shaft.

The undulating surfaces 90 and 92 define a series of alternate crests and valleys defining cam surfaces. As illustrated, surface 90 includes six equally spaced crests 94, and surface 92 includes a corresponding number of crests 98 offset circumferentially so as to be disposed substantially in axial alignment midway between the crests 94 as is most clearly seen for example in FIG. 10..

As seen in FIGS. 6, 10 and 11, another cam surface or track is provided on the central portion of the outer periphery of the rotor 28, this cam track including a plurality of depressed or flatter portions 100 interconnected with the adjacent portions of the outer periphery of the rotor by gradually sloping surfaces 102. The drawings are to scale in this regard. This cam track 100, 102 is adapted to cooperate with certain valves of a flow control means hereinafter described.

A plurality of pistons are reciprocably received by bores 54, 56, 6 as shown. These pistons 110 are of identical configuration, and a typical piston 110 is illustrated in FIG. 1. Each piston 110 is cylindrically shaped and provided with heads 112 and 114 at the opposite ends thereof, thereby defining variable volume chambers 113 and 115, respectively, with the cylinder bores 36, 54 on the one hand and 56, 38 on the other. Seals I16 and 118 are disposed in peripheral grooves in the respective heads 112, 114 to provide fluidtight seals between the heads and the associated bores.

Each piston 110 is provided in one side with an opening 120 midway between its ends for receiving the cam portion 90, 92 of the rotor 28. Internally of the piston 110 and extending axially opposite from the opening 120 are two elongated cavities 122 and 123, respectively, these cavities 122, 123 being axially in line with cam surfaces 90 and 92.

A pair of shafts 124 are transversely mounted in the piston to extend diametrically across the respective cavities 122, 123, as shown. A bearing is supported on each shaft 124, each bearing including a frustoconical roller 126. This roller is shaped complementary to the slope of the associated surface 90 or 92 on the rotor whereby each roller 126 engages and rolls along a respective one of the surfaces 90 or 92, Each roller 126 is supported by needle bearings 128 for rotation about the associated shaft 124, and a spacer 130 is provided for maintaining the rollers in the operative position illustrated. Each piston 110 accordingly carries a pair of axially spaced bearings 126, 128 which engage the cam surfaces 90 and 92, respectively, of the rotor. The rollers 126 are mounted in such position that the axes thereof extent. parallel to the radii of the rotor. The pistons 110 are held in proper rotational position by arcuate bottom surfaces 121 (see FIG. 1) of the openings 120 which complement in shape and size the cylindrical surface of the rotor 28 in free but close fitting relation.

Referring now to FIG. 2, a first hydraulic fitting connected to the manifold 34 has a port 142. A similar fitting 144 is connected to a diametrically opposite portion of the manifold 34 and includes a port 146.

A first plurality of circumferentially spaced valves 150, 152, 154 and 156 (FIG. 2) are each operatively associated with port 142 and a second plurality of circumferentially spaced valves 160, 162, 164 and 166 are operatively associated with port 146 as hereinafter described. The valves are identically constructed and comprise a poppet-type valve described in more detail later. As seen in FIG. 3, the construction of one of the valves 156 includes an insert 170 externally threaded at the opposite ends, the lower end as viewed in FIG. 3 being of smaller diameter. This smaller end is threaded into an internally threaded bore 172 formed in manifold 34 which opens through the inner wall of the latter. Insert 170 has a central cylindrical bore 174 for slidably mounting the poppet valve described later. The insert 170 is adjustable by means of a the threaded mounting within the manifold 34 to make allowance for machining tolerances.

A pair of spaced rubber O-ring seals are mounted within suitable peripheral grooves in the outer surface of insert 170. An annular groove 182 in the outer surface of the insert 170 communicates through suitable drilled passages 188 (shown in FIGS. 4 and 13) in the manifold 34 with the ports 142 and 146 (FIGS. 2,4 and 13). As seen in FIGS. 4 and 13, ports 142 and 146 communicate with respective cavities 186 in the manifold 34 and passages 188 drilled therein. The drilled passages 188 (see FIGS. 4 and 13) connect ports 142 and 146 with the annular passage 182 of valve 156.

Referring again to FIG. 3, annular passage 182 communicates with a plurality of radially inwardly extending passages 190 which in turn communicate with a the bore 174. Bore 174 communicates with an enlarged upper bore 192. A plurality of circumferentially spaced short radial passages 194 connect bore 192 with annular passage .6 which in turn communicates with drilled passages 198 in manifold 34 assages 198 are in communication with passages 200 which extend through annular body members 30 and 32, these passages 200 in turn communicating with suitably drilled passages (l." r described in connection with FIGS. 14 and 15) in cylinder heads 36 and 38 for providing communication between ports 142, 146, the various valves 150 et al. and the cylinders 54, 56, 60 within which the various pistons reciprocate.

Valve 156 includes an internally threaded cup-shaped cap 204 received on the threaded upper portion of the insert 170. An O-ring seal 206 is seated within a suitable groove in the cap to provide a seal with the outer surface of the manifold 34.

A valve member 210 includes a generally frustoconical poppet valve 212 adapted to seal on an annular seat in the insert 170 fonned by an annular shoulder separating the bores 174 and 192, The valve member 210 is normally biased downwardly into the sealing position by a compression spring 214 disposed between the valve member and the cap 204.

The valve member 210 includes an intermediate portion 218 of reduced diameter and a lower tappet portion 220 which fits relatively snugly within bore 174. An O-ring 222 is disposed within a circumferential groove formed in the tappet 220 to provide a seal with respect to the bore 174.

The end 226 of the tappet 220 is curved and engages slidably the outer surface of the rotor 28 and the cam track 100, 102 whereby the poppet valves 212 are operated between opened and closed position in response to rotation of the rotor 28.

In the position shown in FIG. 3, the end 226 engages depressed portion shown in FIG. 3, the end 226 engages depressed portion 100 to the track 100, 102 which enables the valve 212 to be closed by compression spring 214. It is apparent that when the tappet rides up onto the outer periphery of the rotor 28, the valve 212 will be opened providing communication between annular passages 182 and 196.

Referring now to FIG. 12 of the drawings, the arrangement of the present invention is illustrated schematically whereby the arrangement for controlling fluid flow to the various cylinders and pistons may be readily understood. Partscorresponding to those previously described have been given the same reference numerals. Pistons 110 at the lower portion of the figure corresponds to piston 110 as shown in FIG. 1 of the drawings. Seven like pistons 230, 232, 234, 236, 238, 240 and 242 are provided, these pistons also being mounted for reciprocation within the respective bores equally circumferentially spaced in the carrier 31 (FIGS. 1 and 4) whereby eight pistons in all are provided.

Port 146 (upper right-hand side of FIG. 12) is in communication with each of poppet valves 160, 162, 164 and 166 by drilled passages 188 in manifold 34 (FIGS. 4 and 13). Port 142 (lower right-hand side of FIG. 12) is similarly in communication with each of poppet valves 150, 152, 154 and 156 by similar drilled passages 188 also provided in the manifold 34.

As shown in this FIG. 12, the cam track 100, 102, which for illustrative purposes is developed into a flat plane, is moving in the direction of arrow A with respect to the poppet valves which are mounted in the stationary manifold 34, and rotor 28 is moving in the direction indicated by arrow B with respect to the pistons which are reciprocable within the stationary carrier 31.

In the position illustrated, valves 156, and 166 are in the process of closing. Valves 154 and 164 are closed. Valves 152 and 162 are in the process of opening, and valves 150 and 160 are open.

The passages hereinafter described providing communication between the various poppet valves and the cylinders are understood to be the drilled passages which are partly formed in the manifold 34, the two cylinder bodies or. blocks 30 and 32, and also in the cylinder heads 36 and 38 (see later description in connection with FIGS. 14 and 15).

It should be understood that ports 142 and 146 are suitably connected with a source of pressure fluid such as a pump, reservoir or the like. Depending upon the direction of rotation of the motor, one of these ports 142, 146 will be an inlet port and the other an outlet port. As shown, port 142 is the inlet port whereby fluid pressure passes inwardly through port 142 to the various cylinders and pistons. Accordingly, port 146 is an outlet port and may be connected to a return line operatively associated with a return tank, exhaust reservoir or the like.

In FIG. 12, valve 150 is shown open. This valve 150 is in communication with a passage 250 which in turn communicates with passage 252. Passage 252 communicates with passage 254 which supplies fluid under pressure to the righthand end of piston 230, driving the latter to the left as seen in the drawing, thereby forcing the rotor 28 to move in the direction of arrow B by the cooperation of the bearing 126 and the associated cam surface 92.

Passage 252 is also in communication with passage 256 whereby fluid under pressure is applied to the right-hand end of piston 238 to drive piston 238 to the left. Passage 252 also communicates with passages 258 and 260, forcing the associated pistons 242 and 234 to the right as seen in FIG. 12 which also tends to move the rotor 28 in the direction of arrow B.

In FIG. 12, valve 160 is s also open. This valve is in communication with passages 264, 266, 268 270, 272 and 274 which connect with the opposite ends of pistons 242, 234, 238 and 230, respectively. Since pistons 242 and 234 are moving toward the right, and pistons 238 and. 230 toward the left, fluid is exhausted from the respective cylinders through valve 160 and port 146.

Valve 154 which is closed in the position illustrated is connected by passage 280 with the aforedescribed passage 266. Valve 164 which is also closed as seen in this figure is connected by passage 282 with the aforedescribed passage 252.

Valve 152 which is in the process of opening is connected by passage 290 with a passage 292. Passage 292 communicates with passage 294, 296, 298, 300 which lead to the cylinders containing pistons 236, 110, 232 and 240, respectively.

Valve 166 by means of passage 302 also communicates with passage 292.

Valve 156 which is in the process of closing is in communication with passages 310, 312 and 314 which communicate with the right-hand end of the cylinder containing piston 232. Passage 312 is also in communication with a passage 3116 connecting to the right-hand end of the cylinder containing piston 240.

Passage 312 also connects via passage 320 to the left-hand end of the cylinder containing piston 110. Passage 312 further connects via passage 322 to the left-hand end of the cylinder containing piston 236.

It is apparent that as the cam track 100, 102 moves in the direction of arrow A as seen in FIG. 12, the valves will be opened and closed in sequence so as to reciprocate the pistons whereby the bearings on each of the pistons coacts with the outer surface 90, 92 to drive the rotor 28 in the direction of the arrow B.

In order to reduce the number of poppet valves required to a minimum, the sixteen (16) piston heads working in a like number of cylinder chambers are connected into four groups of four with an inlet port and an outlet port connected to each group. Each group of piston heads includes one pair thereof disposed 180 apart in the carrier 31 atone side or end of the motor and a second pair disposed 180 apart in the carrier 31 at the opposite side or end but rotated from the first pair. For example, pistons 230 and 238 are diametrically opposite as are pistons 234 and 242. The pair 230, 238 are angularly spaced 90 from the pair 234 and 242.

A minimum of four and a maximum of eight piston heads are available at a time to produce power. In the operating positions shown in FIG. 12, pistons 230, 238, 234 and 242 are imparting rotational power to rotor 28. In the next instant after camtrack 100, 102 has moved to open valve 152, an additional four pistons 110, 236, 232 and 240 will apply power making the total eight.

When the pistons are in registry with the crests and valleys 89 and 91, respectively, as pistons 110, 232, 236 and 240 are shown in FIG. 12, they are on dead center" and all valves connected thereto are in the process of changing between previously opened or closed condition to closed or opened condition, respectively, as the case may be.

Taking piston as an example, piston head 112 has just finished its power stroke during which pressure valve 156 was opened and exhaust valve 162 was closed. These valves as depicted are now reversing, valve 156 preparing to close and valve 162 preparing to open. Likewise, piston head 114 has just finished its return or exhaust stroke during which pressure valve 152 was closed and exhaust valve 166 was opened. These valves are now reversing as illustrated, valve 152 preparing to open and valve 166 preparing to close.

Cam track 100, 102 is so formed that in the next instant rotor 28 will have rotated sufficiently that piston head 114 with its roller 126 will engage power-applying slope 93 and the head 112 with return slope 95, and the valves 156, 162, 152 and 166 will have completed reversal whereupon piston head 114 now applies power and piston head 112 starts its exhaust stroke. The other pistons 232, 236 and 240 experience the same reversal of operation as can be determined by tracing the schematic (FIG. 12).

The cam track 100, 102, the pattern of undulations on cam surfaces 90, 92 and the location of the pistons 110,230, 232, 234, 236, 238, 240 and '242 are so correlated as shown that the application of rotational power to the rotor 28 occurs only when the pressurized piston heads are operationally engaged with the power-applying slopes" 93 and the depressurized piston heads are similarly engaged with the return slopes 95. Further they are so correlated as shown as to produce substantially constant torque by relating the different slope angulations with different pressurized piston heads such that at one instant one piston head exerts more rotational power onthe rotor 28 than does another.

The piston heads exerting power are also geometrically arranged that the rotor 28 has applied to opposite sides thereof (sides of surfaces 90, 92) equal forces which thereby result in the rotor 28 having no unbalanced axial force being applied thereto. This arrangement is also such that every pressurized piston head on one side (e.g., surface 90) of the rotor 28 has another diametrically opposite, such that balanced forces are applied diametrically.

The cam surfaces 90 and 92 (drawn substantially to scale) each have a variable slope as seen for example in FIG. 10 of a configuration known as a constant acceleration cam which permits positioning the rollers 126 of a group of pistons under power on the steepest part of the slope while a second group of pistons is on dead center at the crests.

I convenience as power-applying" and return slopes. The

power-applying slopes" are the common ones indicated by the numeral 93 (FIG. 12) and are the slopes with which the pistons are engaged when pressurized. The return slopes are the opposite ones indicated by the numeral 95 (FIG. 12) and are the ones in registry with the pistons when fluid is being exhausted therefrom.

Inasmuch as cam track 100, 102 serves in the function of synchronizing pressurization and depressurization of the pistons when engaged with the power-applying and return slopes, it may conveniently be referred to as a synchronizing cam.

It should be noted that the pistons are actuated in a definite geometric pattern wherein two pistons spaced 180 from one another on one side of the motor are operating simultaneously with two other pistons spaced 180 apart at the opposite side of the motor but rotated 90 with respect to the first two.

The six crests on each surface 90, 92 will cause 6 complete cycles of each piston for each revolution of the output shaft 20.

All of the various lines and passages shown schematically in FIG. 12 may be obtained solely by passages formed in the various parts, such as the manifold 34, the annular cylinder bodies 30, 32, and the cylinder heads 36, 38, or in part may be supplied by conventional copper tubes and fittings external to the motor assembly. Preferably, however, to provide a more compact structure, all of the passages are provided internally of the rotor parts as will now be explained. Certain of the passages have already been described as being drilled in the manifold member 34 as shown in FIGS. 1, 3 and 13. Also as noted in connection with FIG. 3, drilled passages 200 are provided in the annular cylinder bodies 30 and 32. As generally explained earlier, other connecting passages are formed in the cylinder heads 36 and 38, and in the following the passage configuration in these heads 36 and 38 will be described. For this purpose, reference is had to FIGS. 3, l4 and 15. Inasmuch as drilled passages must be straight, it is necessary to lay out a system of straight passages with appropriate intersections whereby the various hydraulic interconnections shown in FIG. 12 may be achieved. FIGS. 14 and 15 illustrate only the cylinder head 36. However, it should be understood that the cylinder head 38 is identical in the respect of being a mirror replica. A description of the head 36 therefore will suffice for both.

Referring to FIGS. 14 and 15, it will be noted that there are, generally speaking, two series of drilled passages denoted by the IettersX and Y, respectively. FIG. 15 illustrates this characterization, the passages X being at one depth in the thickness of the head 36 while the passages Y" are at at a different depth. This permits crisscrossing of the passages X and Y without intercommunication.

Since the passages are drilled, the drill must penetrate the periphery of the head 36 such that it becomes necessary to plug the openings in the periphery. For example, passage 203 (FIG. 14) is drilled radially inwardly at X depth parallel to the opposite surfaces of the head 36 and is plugged by means of a weld 207 or the like. Other plugs are denoted by numeral 207a. The passage 205, again referring to FIG. 14, is drilled through the periphery along a chord of the circular head so as to intersect with the end of the passage 203.

A transverse passage 201 is drilled through the inner side of the head 36 as shown more clearly in FIG. 3, thereby providing a right-angle passage 201, 203. Another transverse passage 209 (see FIGS. 1 and 14) is drilled into the head 36 to intersect one end of the passage 205 a s shown. The opposite end of the transverse passage 209, as shown more clearly in FIG. 1, opens into the chamber 113 which communicates with the piston head 1 12.

The drilled passage 201 (FIGS. 3 and 14) is so positioned as to register precisely with the drilled passage 200 previously described. Thus, communication of pressure fluid is provided from the valve 156 (FIG. 3) through the passages 198, 200, 201,203, 205 and 209 to the chamber 113 in the cylinder containing piston head 1 12.

Since it is necessary to establish communication with a piston that is diametrically opposite the piston 110, another drilled passage 211 which communicates with one end of the passage 205 is drilled as shown in FIG. 14. This passage terminates in a transverse passage 294 (also see FIG. 12) which communicates with the chamber 113 for the piston 236. The dashed line circles noted in FIG. 14 denote the relative positions of the various pistons and not any particular structure in the head 36.

It will be noted that the pistons 110 and 236 are diametrically opposite and that they are interconnected to the same pressure fluid line composed of the passages 201, 203, 205, 211 and 294. Thus, the admission of pressure fluid to, for example, the passage 201 will result in communication of the same fluid to the pistons 1 10 and 236.

Inasmuch as communication of the same pressure fluid must be established to more piston heads on the opposite side of the motor 28 but spaced away from the first two pistons and 236, it is necessary for a hydraulic passage to be established which passes through to the opposite side of the motor, or in other words to the cylinder head 38. This is accomplished by means of another passage 213 which extends from a transverse passage 215 communicating with the same piston chamber as the passage 209. The opposite end of the passage 213 terminates in another transverse passage 217 which connects with a suitable transverse passage (not shown) in the cylinder body 30, the manifold 34, the other cylinder body 32, and then to a transverse passage in the head 38. As explained previously, the head 38 insofar as the passage design is concerned is a mirror replica of that of the head 36. Communication is thereby established in the head 38 by the same pattern of drilled passages to the cylinders containing pistons 232 and 240. Thus it is shown that the same fluid connected to the chamber 113 containing the piston head 114 is also communicated to the corresponding piston heads of the pistons 236, 232 and 240. The reminder of the pistons and cylinders are similarly connected so as to obtain the conduit pattern shown in FIG. 12.

As explained previously, however, in order to obtain an operative motor, it is not necessary that this pattern of internally drilled passages be used but instead external conduit of copper tubing or the like may be used.

One of the features of advantage in this invention resides in the two-headed piston construction wherein side thrust because of a power engagement with the cam surface on the rotor 28 sis taken by the end of the piston structure which at the moment is exhausting. Thus, this particular piston design many be considered a sliding hearing or crosshead construction herein the side loads are more efficiently carried. in prior art designs which did not use this crosshead arrangement, side thrust tended to cock the piston in its cylinder, thereby producing binding and rapid wear. In the present invention, the side thrust applied at the center of the double-headed piston construction is evenly applied, giving uniform load distribution without added guides or bearings.

The bearings 126, 128 are held in perfect alignment with the cam 90, 92 by means of the close fit of the cutout sections in the pistons with the periphery of the rotor 28. This, therefore, eliminates the need for extra parts, such as guides, to prevent rotation of the pistons in the respective cylinders.

Of substantial importance in this invention is the fact that in prior art hydraulic motors, rotary sliding valves were used to control oil flow to and from the various cylinders. While simple in construction, such sliding valves have inherent leakage, which allows the motor to creep" under an external load. Also, such leakage permits some oil to flow without causing the motor to rotate. This prevents use of the motor in applications requiring the shaft 20 to lock into position when stopped, or for extremely slow speeds. The present invention utilizes poppet valves, which have no leakage, which permit the motor to be locked in position.

The parallel piston arrangement working against a cylindrical cam having two or more undulations combined with pop pet-type valves permits obtaining a motor design which develops extremely high torques and low speed with positive locking action as may be desired.

While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of the invention.

1 claim:

1. A torque motor comprising a generally cylindrical rotor having two generally circular undulating cam surfaces coaxially surrounding said axis, said cam surfaces facing axially oppositely and generally defining the ends of the cylindrical ro-' tor, force-generating means responsive to pressure fluid and operatively engageable with both said cam surfaces for rotating said rotor, valve means for controlling the application of pressure fluid to said force-generating means, said valve means including a valve having a seat with which it selectively forcefully engages for sealing against flow of pressure fluid either to or from said force-generating means.

2. The torque motor of claim l in which said forcegenerating means includes a plurality of two-headed pistons guided for reciprocation parallel to said axis in power cylinders which are stationary with respect to said rotor, respectively, each cylinder having opposite ends and receiving one piston, each said piston defining two variable volume chambers in its cylinder between the piston heads and cylinder ends, respectively, said valve means including meansfor communicating pressure fluid alternatively to each of said two chambers whereby pressure fluid admitted to one chamber forces the respective piston in one direction and pressure fluid admitted to the other chamber forces the piston in the opposite direction.

lit)

3. The torque motor of claim 2 wherein said pistons are circularly arranged and circumferentially spaced to surround coaxially said axis, a first set of two of said pistons being disposed diametrically opposite each other, another set of two of said pistons being disposed diametrically opposite but shifted angularly with respect to the first two, and said valve means including means for applying pressure fluid to said first and second sets to force'them in opposite directions parallel to said rotor axis.

4. The torque motor of claim 2 wherein said pistons are circularly arranged and circumferentially spaced to surround coaxially said axis, said pistons each having bearing means intermediate the ends engaging both said cam surfaces whereby he fluid force applied to either piston head may be imparted to said rotor, and said two cam surfaces have crests and valleys arranged in predetermined relation such that said bearing means of one piston in a given instant engages a crest of one cam surface and the valley of the other cam surface.

5. The motor of claim 4 wherein said pistons each are elongated thereby having a longitudinal axis, each piston having an open side midway between the ends thereof and an elongated cavity along said longitudinal axis, said pistons receiving through the open sides thereof the outer peripheral portion of said rotor, the cavities of said pistons receiving said cam surfaces, and said bearing means being disposed within said cavities.

6. The motor of claim 5 wherein said bearing means for each piston includes tow rollers in the cavity mounted on the piston for rotation about an axis parallel to a radius of said rotor, said rollers being spaced apart longitudinally of the piston so as to engage the respective two cam surfaces, the outer periphery of said rotor being cylindrical, each said piston having an arcuate portion in registry with the open side thereof which complements the shape and side of the rotor periphery but slightly clears the same to provide a free sliding fit therebetween whereby the piston is prevented from rotating within its cylinder.

7. The motor of claim 6 in which said cylinders are disposed within a carrier which is stationary with respect to said rotor, said carrier substantially enclosing said rotor and including an annular manifold member which coaxially surrounds in radial registry said rotor, said carrier further including two annular elements secured to opposite sides, respectively, of said manifold member, said annular elements including a plurality of circumferentially arranged bores which serve as parts of said power cylinders, the bores of one element being axially aligned with the bores of the other elements and parallel to the rotor axis, two annular plates serving as cylinder heads secured to the outer sides, respectively, of said annular elements for closing said bores and thereby defining said variable volume chambers, said valve and seat portion of said valve means being carried by said manifold member.

8. The motor of claim 7 wherein said rotor is provided with a cam track in its outer periphery which includes a series of peripherally spaced raised and depressed portions, said valve means including a plurality of poppet valves circumferentially spaced and mounted in said manifold member, each said poppet valve having a tappet operatively engaging said cam track whereby rotation of said rotor results in alternate opening and closing said valve.

9. The motor of claim 8 in which said rotor cam surfaces are regularly undulating with the crests of one cam surface being axially opposite the valleys of the other, said valve means further including a series of passages in said manifold member, said annular elements, and said heads which interconnect predetermined ones of said poppet valves with predetermined ones of said variable volume chambers.

10. The motor of claim 9 in which the number and location of pistons and undulation in the cam surfaces are so related that two different pistons will have rollers capable of engaging different portions of power-applying slopes of different undulations whereby at a predetermined instant rotational power maybe applied to said rotor by both of the last-mentioned pistons, said number and location of pistons and undulations further being so arranged that at a different instant at least one of said pistons will have its roller engaging a power-applying slope whereby at all times rotational power may be applied to said rotor, said cam surfaces further being shaped as constant acceleration cams.

11. The motor of claim in which there are an equal number of pistons and poppet valves, said series of passages and said cam track being so arranged that said poppet valves will be operated in sequence such that at any time when pressure fluid is being admitted to one variable volume chamber that said poppet valves will be operated in sequence such that at any time when pressure fluid is being admitted to one variable volume chamber the other chamber for the same piston will be exhausted.

12. The motor of claim 3 in which said valve means includes synchronizing cam means responsive to rotation of said rotor for communicating pressure fluid to said variable volume chambers and exhausting fluid from the opposed variable volume chambers in a predetermined sequence, the undulations of said cam surfaces including power-applying slopes so spaced relative to said pistons that at the time pressure fluid is being admitted to one chamber the piston thereof is operatively engaged with a power-applying slope on one cam surface, and at the time pressure fluid is being admitted to the other chamber for the cam piston, the piston is operatively engaged with a power-applying slope on the other surface.

13. The torque motor of claim 2 in which said undulations include power-applying and return slopes. the number and spacing of cam undulations and pistons being such that at least one piston operatively engages a power-applying slope at all times during rotation of said rotor, said undulations furtherbeing arranged such that a piston operatively registers simul taneously with both power-applying and return slopes of the two cam surfaces, respectively, and means synchronizing operation of said valve means such that said pistons will be reciprocated according to a predetermined sequence such that whenever pressure fluid is being admitted to a chamber the piston thereof will be operatively engaged with a powerapplying slope.

14. The torque motor of claim 13 wherein said pistons are arranged in groups, there being at least two pistons in each group, the pistons of each said group being synchronized to engage similar portions of different ones of said power-applying slopes at the same time, and said valve means includes a plurality of poppet valves for introducing pressure fluid to said pistons, there being one poppet valve for each said group in a one for one correspondence, each said poppet valve being coupled to a different one of said groups for simultaneous introduction of pressure fluid thereto.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 536 Dated A g 7 LESTER L. MYERS Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE SPECIFICATIONS Column 1, Line 17, change "is" to ---in- Column 1, Line 21, after "sliding" insert ---valves to--- Column 1, Line 69, after "torque" insert --output--- Column 2, Line 59, change "2 to --29-- Column 3, Line 2, change "ill" to --will-- Column 4, Line 38, after "of" delete "a" Column 4, Line 44, change "suitable" to --suitably--- Column 4, Line 50, after "annular" insert --passages in the various valve inserts 170 similar to annular--- Column 4, Line 52, after "inwardly" insert ---upwardly-- Column 4, Line 53, after "with" delete a" Column 5, Lines 12-13, after "portion" delete "shown in Fig. 3,

the end 226 engages depressed portion" Column 5, Line 13, change "to" to --of-- Column 5, Line 24, change "Pistons" to ---Piston-- Column 6, Line 19, change "passage" to --passages--- Column 7, Line 70, change "rotor" to ---motor--- Column 8, Line 61, change "motor" to --rotor-- Column 9, Line 4, change "reminder" to ---remainder-- Column 9, Line 14, after "28" delete "5'' Column 9, Line 16, change "many" to may--- Column 9, Line 17, change "herein" to -wherein--- IN THE CLAIMS Claim 4, Column 10, Line 15, change "he" to --the- Claim 6, Column 10, Line 29, change "tow" to ---two--- Claim ll,Column 11, Lines 11-13, delete "that said poppet valves will be operated in sequence such that at any time when pressure fluid is being admitted to one variable volume chamber" JRM PO-1050 (10-69) USCOMM-DC BO376-P69 Q U 5 GOVERNMENT PRINTING OFFICE I969 O-3i6-33l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION August 17, 1971 Patent No. 31 1 Dated PAGE 2 LESTER L. MYERS Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE CLAIMS Line 1, after "other" insert -cam- Claim 12. Column 12,

Signed and sealed this 18th day of April 1972.

( SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer DRM PO-1050 (10-69) USCOMM-DC 6O376-F'6fl u S GOVERNMENY PRINY NG OFFICE $909 0-356-334 

1. A torque motor comprising a generally cylindrical rotor having two generally circular undulating cam surfaces coaxially surrounding said axis, said cam surfaces facing axially oppositely and generally defining the ends of the cylindrical rotor, force-generating means responsive to pressure fluid and operatively engageable with both said cam surfaces for rotating said rotor, valve means for controlling the application of pressure fluid to said force-generating means, said valve means including a valve having a seat with which it selectively forcefully engages for sealing against flow of pressure fluid either to or from said force-generating means.
 2. The torque motor of claim 1 in which said force-generating means includes a plurality of two-headed pistons guided for reciprocation parallel to said axis in power cylinders which are stationary with respect to said rotor, respectively, each cylinder having opposite ends and receiving one piston, each said piston defining two variable volume chambers in its cylinder between the piston heads and cylinder ends, respectively, said valve means including means for communicating pressure fluid alternatively to each of said two chambers whereby pressure fluid admitted to one chamber forces the respective piston in one direction and pressure fluid admitted to the other chamber forces the piston in the opposite direction.
 3. The torque motor of claim 2 wherein said pistons are circularly arranged and circumferentially spaced to surround coaxially said axis, a first set of two of said pistons being disposed diametrically opposite each other, another set of two of said pistons being disposed diametrically opposite but shifted 90* angularly with respect to the first two, and said valve means including means for applying pressure fluid to said first and second sets to force them in opposite directions parallel to said rotor axis.
 4. The torque motor of claim 2 wherein said pistons are circularly arranged and circumferentially spaced to surround coaxially said axis, said pistons each having bearing means intermediate the ends engaging both said cam surfaces whereby he fluid force applied to either piston head may be imparted to said rotor, and said two cam surfaces have crests and valleys arranged in predetermined relation such that said bearing means of one piston in a given instant engages a crest of one cam surface and the valley of the other cam surface.
 5. The motor of claim 4 wherein said pistons each are elongated thereby having a longitudinal axis, each piston having an open side midway between the ends thereof and an elongated cavity along said longitudinal axis, said pistons receiving through the open sides thereof the outer peripheral portion of said rotor, the cavities of said pistons receiving said cam surfaces, and said bearing means being disposed within said cavities.
 6. The motor of claim 5 wherein said bearing means for each piston includes tow rollers in the cavity mounted on the piston for rotation about an axis parallel to a radius of said rotor, said rollers being spaced apart longitudinally of the piston so as to engage the respective two cam surfaces, the outer periphery of said rotor being cylindrical, each said piston having an arcuate portion in registry with the open side thereof which complements the shape and side of the rotor periphery but slightly clears the same to provide a free sliding fit therebetween whereby the piston is prevented from rotating within its cylinder.
 7. The motor of claim 6 in which said cylinders are disposed within a carrier which is stationary with respect to said rotor, said carrier substantially enclosing said rotor and including an annular manifold member which coaxially surrounds in radial registry said rotor, said carrier further including two annular elements secured to opposite sides, respectively, of said manifold member, said annular elements including a plurality of circumferentially arranged bores which serve as parts of said power cylinders, the bores of one element being axially aligned with the bores of the other elements and parallel to the rotor axis, two annular plates serving as cylinder heads secured to the outer sides, respectively, of said annular elements for closing said bores and thereby defining said variable volume chambers, said valve and seat portion of said valve means being carried by said manifold member.
 8. The motor of claim 7 wherein said rotor is provided with a cam track in its outer periphery which includes a series of peripherally spaced raised and depressed portions, said valve means including a plurality of poppet valves circumferentially spaced and mounted in said manifold member, each said poppet valve having a tappet operatively engaging said cam track whereby rotation of said rotor results in alternate opening and closing said valve.
 9. The motor of claim 8 in which said rotor cam surfaces are regularly undulating with the crests of one cam surface being axially opposite the valleys of the other, said valve means further including a series of passages in said manifold member, said annular elements, and said heads which interconnect predetermined ones of said poppet valves with predetermined ones of said variable volume chambers.
 10. The motor of claim 9 in which the number and location of pistons and undulation in the cam surfaces are so related that two different pistons will have rollers capable of engaging different portions of power-applying slopes of different undulations whereby at a predetermined instant rotational power maybe applied to said rotor by both of the last-mentioned pistons, said number and location of pistons and undulations further being so arranged that at a different instant at least one of said pistons will have its roller engaging a power-applying slope whereby at all times rotational power may be applied to said rotor, said cam surfaces further being shaped as ''''constant acceleration cams.''''
 11. The motor of claim 10 in which there are an equal number of pistons and poppet valves, said series of passages and said cam track being so arranged that said poppet valves will be operated in sequence such that at any time when pressure fluid is being admitted to one variable volume chamber that said poppet valves will be operated in sequence such that at any time when pressure fluid is being admitted to one variable volume chamber the other chamber for the same piston will be exhausted.
 12. The motor of claim 3 in which said valve means includes synchronizing cam means responsive to rotation of said rotor for communicating pressure fluid to said variable volume chambers and exhausting fluid from the opposed variable volume chambers in a predetermined sequence, the undulations of said cam surfaces including power-applying slopes so spaced relative to said pistons that at the time pressure fluid is being admitted to one chamber the piston thereof is operatively engaged with a power-applying slope on one cam surface, and at the time pressure fluid is being admitted to the other chamber for the cam piston, the piston is operatively engaged with a power-applying slope on the other surface.
 13. The torque motor of claim 2 in which said undulations include power-applying and return slopes, the number and spacing of cam undulations and pistons being such that at least one piston operatively engages a power-applying slope at all times during rotation of said rotor, said undulations further being arranged such that a piston operatively registers simultaneously with both power-applying and return slopes of the two cam surfaces, respectively, and means synchronizing operation of said valve means such that said pistons will be reciprocated according to a predetermined sequence such that whenever pressure fluid is being admitted to a chamber the piston thereof will be operatively engaged with a power-applying slope.
 14. The torque motor of claim 13 wherein said pistons are arranged in groups, there being at least two pistons in each group, the pistons of each said group being synchronized to engage similar portions of different ones of said power-applying slopes at the same time, and said valve means includes a plurality of poppet valves for introducing pressure fluid to said pistons, there being one poppet valve for each said group in a one for one correspondence, each said poppet valve being coupled to a different one of said groups for simultaneous introduction of pressure fluid thereto. 